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Carbon nanotubes (CNTs) are grown using plasma enhanced chemical vapor deposition (PECVD). A modified radio frequency (RF) parallel-plate plasma etching system serves as the growth reactor. The effects of process parameters, including temperature, pressure, and C2H2:NH3 ratio, are studied. CNTs are grown on glass substrates with Al underlayers and Ni catalyst layers, which are deposited through ion beam sputtering (IBS). Analysis of the catalytic surface is performed by atomic force microscopy (AFM). Growth morphology and composition is characterized with scanning electron microscopy (SEM) and energy dispersive
x-ray (EDX) spectroscopy. CNTs are found to grow in four of eight design of experiment (DOE) growth trials and also in a independent ninth growth trial. Growth rate, which is a function of the process parameters and CNT diameters, is found to vary between 60 and 500 nm/min.
Growth exhibited diameters of ~15-70 nm. The wide range of diameters suggests that the current IBS deposition method and annealing step may produce catalyst particles with inconsistent diameters. |
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